Colloids were localized and tracked using Blair and Dufresne’s publicly available Matlab version of the particle tracking code originally developed by Crocker and Grier [1]}. Particle trajectories were de-drifted to remove the effects of residual bulk flows in the sample as well as any drift in the microscope stage. Clusters were identified using a distance cutoff. Two colloids separated by less than 1.2\(\sigma \) , where \(\sigma \)  is the colloid diameter, were classified as belonging to the same cluster.
